Browsing by Author "Oter, Cigdem"

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Adsorption Behaviours of Th(Iv) and U(Vi) Using Nitric Acid (Hno3) Modified Activated Carbon: Equilibrium, Thermodynamic and Kinetic Studies
(Taylor & Francis Ltd, 2021) Oter, Cigdem; Zorer, Ozlem Selcuk
In order to research the sorption of thorium(IV) and uranium(VI) ions from aqueous solutions, the granular-activated carbon was modified with nitric acid. The modified adsorbent was identified by BET, elemental analysis, SEM and FTIR method. The influences of different parameters such as pH, contact time, temperature and initial concentration were investigated using batch system. Adsorption of Th(IV) and U(VI) onto modified carbon has been evaluated in terms of equilibrium, kinetics and thermodynamics studies. When the obtained results of thorium(IV) and uranium(VI) sorption onto modified adsorbent was applied to kinetic models, it was observed that the experimental results much better fitted the pseudo-second-order kinetic model. Adsorption process was better explained by Langmuir isotherm in comparison with other isotherms. Thermodynamic data were calculated from the sorption isotherms. Results suggested that the adsorption of Th(IV) and U(VI) on modified adsorbent was an endothermic and spontaneous process.
Kinetic, Isothermal and Thermodynamic Studies on Th(Iv) Adsorption by Different Modified Activated Carbons
(Springer, 2020) Oter, Cigdem; Zorer, Ozlem Selcuk
In this study, the performance of modified adsorbents obtained from activated carbon for the adsorption of thorium(IV) ions from aqueous media was investigated. The analytical and spectroscopic methods such as FT-IR, BET, SEM and UV-Vis were used to examine the properties of the modified materials. According to the analysis results, the both adsorbents had large surface areas after modification. Then, temperature, pH, mixing time and solution concentration parameters were observed to determine optimum thorium adsorption conditions on modified materials. The obtained results from the experiments were applied different three kinetic models and adsorption isotherms and thermodynamic parameters were calculated and then all of the results were interpreted. The adsorption process for both adsorption systems was observed to be compatible with the pseudo-second-order kinetic model. The adsorption equilibrium data were best described by the Langmuir model for modified adsorbent with KMnO4 and by the Freundlich model for modified adsorbent with NaOH. Furthermore, the calculated thermodynamic parameters (Delta G degrees, Delta H degrees and Delta S degrees) showed that the both adsorption processes were endothermic and spontaneous. The data show that modified adsorbents can be used as influential and low-cost adsorbents to remove thorium ion. Modified new adsorbents were highly selective for thorium ion in competitive adsorption studies.
Molecularly Imprinted Polymer Preparations for Selective Detection of C-Reactive Protein: Thermodynamic and Kinetic Studies
(Wiley, 2023) Oter, Cigdem; Tawfeeq, Abdulqader
C-reactive protein (CRP) is a member of the pentraxin protein group. CRP is considered an acute-phase protein produced by the liver during inflammation in various diseases limited to pathogenic infections. It is very important that serum CRP concentration can be measured quickly, reliably and easily. Therefore, a three-dimensional crosslinked molecularly imprinted polymer (MIP) with selective recognition sites for CRP was synthesized (CRP-MIP) and characterization analyzes (scanning electron microscopy, Fourier transform infrared, and thermogravimetric analysis) were performed. The binding abilities of the synthesized polymers by adsorption of CRP in aqueous solution were evaluated in detail and compared with the abilities of an unprinted polymer (CRP-NIP) used as a reference. It was found that the MIP prepared by the printing effect selectively adsorbed the template molecule CRP. For this effect, the selectivity of MIP toward CRP and various positive acute-phase reactants such as alpha 1-antitrypsin and alpha 1-acid glycoprotein was evaluated and high selectivity toward CRP was obtained. CRP-MIP was used to remove CRP from crude human serum, and the recovery was up to 91%. Adsorption process of CRP from aqueous solutions on polymeric adsorbents; equilibrium was evaluated in terms of kinetic and thermodynamic conditions and the necessary parameters to describe the process were calculated under these conditions. Adsorption data: the pseudo-first order kinetic model, the pseudo-second order kinetic model, the Elovich kinetic model and the intraparticle diffusion model were studied and the thermodynamic parameters Delta G degrees, Delta H degrees, and Delta S degrees were calculated.
Polymeric Adsorbent for the Effective Removal of Toxic Dyes From Aqueous Solutions: Equilibrium, Kinetic, and Thermodynamic Modeling
(Wiley-v C H verlag Gmbh, 2024) Oter, Cigdem; Gokkus, Kutalmis; Gur, Mahmut; Butun, Vural
This study investigates the adsorption behavior of anionic (Congo red, Eosin yellow) and cationic (Malachite green) dyes on synthesized TD polymer particles, highlighting the material's potential as an effective adsorbent for industrial wastewater treatment. Key operational parameters, including initial solution's pH, contact time, initial dye concentration, and temperature, were systematically evaluated to determine their influence on adsorption efficiency. The experimental data demonstrated that the Langmuir isotherm provided the best fit for all three dyes, indicating monolayer adsorption with maximum adsorption capacities of 153.8 mg/g for Malachite green, 49.36 mg/g for Congo red, and 227.9 mg/g for Eosin yellow. Kinetic analysis revealed that the adsorption of Malachite green and Congo red followed pseudo-second-order kinetics, while Eosin yellow adsorption was better described by the intra-particle diffusion model. Thermodynamic assessments, including Gibbs free energy (Delta G degrees), enthalpy (Delta H degrees), and entropy (Delta S degrees), confirmed the spontaneous and endothermic nature of the adsorption processes for Malachite green and Eosin yellow, contrasting with the exothermic behavior observed for Congo red. These findings underscore the versatility and effectiveness of TD polymer particles in removing both anionic and cationic dyes from aqueous solutions. Further research could explore material optimization and real-world applications to broaden their utility in sustainable water treatment strategies.
Preparation a Magnetic Molecular Imprinted Polymer for Specific Adsorption of Pharmaceutical Pollutants
(Wiley-v C H verlag Gmbh, 2023) Oter, Cigdem
Amoxicillin (AMX) is an antibiotic commonly used to treat bacterial and respiratory diseases in humans and animals. In this study, magnetically imprinted polymers (MMIPs) were successfully synthesized and characterized by the surface imprinting method to selectively separate AMX from an aqueous medium. The suitability of kinetic models and isothermal models for the adsorption of AMX from aqueous solutions using magnetic polymers was compared with an unprinted reference polymer (MNIP). The obtained data showed that the adsorption process is compatible with the pseudo-second order kinetic model and Langmuir isotherm. In addition, adsorption selectivity experiments were performed and it was found that the MMIPs exhibited excellent selective adsorption capacity for AMX. The MMIPs possessed an adsorption capacity of 134 mg/g for AMX and the imprinting factor was 2.23. The MMIPs were also recyclable and retained 86 % of their adsorption capacity after 7 cycles. Based on these results, the study provides a sustainable option in terms of high added value, environmentally friendly, flexible, safe, energy efficient and cost effective in terms of effective removal of pollutants and recycling of adsorbents.
Preparation of Versatile Polymer Particles and Their Application for Elimination of Bromophenol Blue and Phenol From Aqueous Environment
(Elsevier Science inc, 2024) Gokkus, Kutalmis; Oter, Cigdem; Amlani, Merilyn; Gur, Mahmut; Butun, Vural
Cellulose, activated carbon, zeolite, and similar materials have a weak effect against anionic pollutants. Therefore, further modifications are needed for the use of such substances. In this study, polymer particles (GD) that were economical and directly effective against anionic pollutants were synthesized as an alternative. GD particles were synthesized with glutaraldehyde and diethylenetriamine as monomers for the first time. The polymer particles were characterized in detail. Then, GD particles were used in the adsorption of anionic Bromophenol blue (BPB) and phenol (PH). As a result, it was determined that i) the adsorption process between GD particles, Bromophenol blue and phenol was chemisorption, ii) the adsorption of BPB and PH on to GD particles obeyed the Langmuir isotherm and pseudo second order kinetic model. pH, temperature, initial dye concentration, adsorbent dosage, and contact time were determined orderly 4, 50 degrees C, 300 mg L-1, 10 mg, and 180 mins for BPB and 5, 50 degrees C, 10 mg L-1, 15 mg, and 30 mins for PH. The maximum adsorption capacities of GD polymer particles for BPB and PH were ascertained as 136.40 mg g-1 and 98.26 mg g-1, respectively. As a result, it was produced economical, simple, feasible, and functional adsorbents against anionic pollutants.
Removal of Lithium From Aqueous Solutions by Solid-Phase Extraction Using Sawdust Loaded With Magnetite Nanoparticles and Study of Apoptosis, Mda and 8-Ohdg Caused by Lithium Toxicity in Fish Brain
(Sage Publications inc, 2023) Oter, Cigdem; Yeltekin, Asli Cilingir; El-Tekreti, Sama Ammer Abbas
Lithium, which has a high industrial value, is an environmental pollutant of concern to those who work with lithium in industry as well as to the general public. Biological parameters such as MDA, 8-OHdG, apoptosis (caspase-3), and acetylcholinesterase (AChE) were studied to determine the toxic effects on the brain tissue of the model organism (Carassius auratus) exposed to high dose lithium. According to the results obtained, it was found that lithium exposure caused oxidative stress with an increase in MDA level over time and, accordingly, DNA damage and apoptosis occured in brain tissue. It was also found that a decrease in AChE activity was observed, and the high levels of MDA, 8-OHdG, and caspase-3 activity obtained in brain tissue supported this result. The solid phase extraction (SPE) method was used to effectively remove lithium, which has unfavorable effects on living organisms, from aqueous solutions. In this method, a sawdust loaded with magnetite nano-particles (MNLS) was prepared as an adsorbent for solid phase extraction by a simple method, and it was characterized. Optimal conditions for the SPE process were defined and it was found that lithium could be removed from solution onto the MNLS surface with a high yield of about 96%. The results of the study are crucial for proposing a simple and applicable high performance method.
Removal of Nafcillin From Aqueous Solution With Green Synthesis Iron Oxide Nanoparticles
(Oxford Univ Press, 2023) Oter, Cigdem
In this study, iron oxide nanoparticles were synthesized from Solanum nigrum L. extract and used to remove nafcillin, which exhibits toxic properties in aqueous solutions. To understand the adsorption behavior of naphcillin on the nanoadsorbent, the optimum conditions, kinetics and isotherm of adsorption were studied in detail. It was found that the adsorption process was consistent with the pseudo-second order kinetic model and Langmuir's isothermal model. The FeONPs adsorbent achieved an adsorption capacity of 116.3 mg/g for nafcillin. It was also found that FeONPs retained similar to 90% of its adsorption capacity after five adsorption-desorption cycles. Apart from the fact that the nanoparticles synthesized in the study are composed of natural ingredients, S. nigrum L. which causes problems in plant cultivation, serves a useful purpose by being used in this method. The results show that this new nanoadsorbent provides an alternative option for the removal of pharmaceuticals and various pollutants in wastewater. [GRAPHICS] .
Solid Phase Extraction for the Determination of Methylene Blue Using Lignocellulosic Biosorbent in Aqueous Solutions
(Springer, 2022) Oter, Cigdem
The recent introduction of a large number of synthetic dyes, which are toxic, mutagenic, and carcinogenic, has made the situation worse by disrupting normal aquatic life. For this reason, the detection and removal of dyestuffs in wastewater become important. In this study, for the extraction of methylene blue, used as solid phase extraction adsorbent, lignocellulosic biosorbent of tea waste activated with ZnCl2 was prepared. The factors affecting its extraction were studied in detail. To determine the sensitivity and certainty of the solid phase extraction process; optimized to have an adsorbent amount (75 mg), wash solvent (3 mL water), loading volume (20 mL), elution solvent methanol/acetic acid (80:20, v/v), and eluent volume (8 mL). As a result of the optimization processes, rates ranging from 94.4% to 98.9% recovery were obtained in methylene blue extraction in aqueous solutions. According to the results obtained, this method can be extensively applied in the efficient removal of colored contaminants.
Synthesis and Characterization of a Molecularly Imprinted Polymer Adsorbent for Selective Solid-Phase Extraction From Wastewater of Propineb
(Springer, 2022) Oter, Cigdem; Zorer, Ozlem Selcuk
Pesticide residues, which have become a critical problem today, negatively affect the living life and cause concern for the future life. Different methods are being developed to eliminate the problems caused by pesticides and pesticide residue analysis. In this study, a new molecularly imprinted polymer (MIP) has been synthesized for using methacrylic acid as the functional monomer and propineb, a fungicide, as the template molecule. The selectivity and binding properties of MIP were compared with non-imprinted polymer (NIP). MIP particles were used as an adsorbent in the solid-phase extraction column, and various extraction parameters were extensively optimized to evaluate the extraction performance. It was determined that under optimum extraction conditions, MIP showed higher selectivity and extraction capacity toward propineb compared to commercial C-18 column and NIP. As a result, the developed solid phase extraction method was optimized for propineb residue analysis, and high extraction efficiency was obtained. This method, which is low cost, requires very little use of organic solvents, is fast and easy, is selective and environmentally friendly, is very useful for the purification of wastewater from pollutants.